Old (steel) or new (rubber) upper and lower control arm bushings?

[68PanelTruck]

Hi guys,
I'm gathering up parts for my 68 panel truck to do a drum to disc brake swap. I am also going to add drop spindles at the same time and rebuild the upper and lower control arms with new upper and lower ball joints, tie rod ends, and control arm bushings . I have two options:

1) use original upper and lower control arms with new, old style greaseable steel bushings and shafts and order the correct drop spindles to fit the 68 ball joints and tie rods.
or
2) I have another set of upper and lower control arms from a 72+ that will get new rubber bushings. I would also order the correct drop spindles to fit the ball joints, etc.

Right now I do have all new Moog 68 tie rod ends, ball joints, sleeves and a idler arm that I bought and can use with either set of arms (68 or 72+) with the correct CPP drop spindles (I think unless I'm missing something?).

Is there any advantage of using the newer rubber bushing control arms over the older style steel bushing control arms? I have not bought any bushings yet so I can use either set of arms. I do understand that the spindles must match the tie rods and ball joints.